Unfortunately, current version of foo_dsp_vlevel plugin will crash foobar2000player when you inactive this plugin. I want to fix this stupid bug,but I cat't find what is wrong. If you know the solution, please send me patch.

I've updated this again. The plugin is now configurable like any other DSP component: from the DSP manager(s). Buffer length is configurable, and the strength control now takes steps of 0.01 instead of 0.1. Note that if you've used the previous version you should properly check the strength control. Grab it here:

I use this dsp inside the converter chain (converting for car audio). Did you people realize it adds significant noise, some kind of metallic hiss artifacts, to tracks? You can hear that especially in the beginning of tracks which start silent.

That's the point of dynamic range compression. Make quiet parts loud and make loud parts quiet. The "dynamic range" is compressed. Less peaks, just one big valley. You're just hearing the background hiss that's already on the track which you don't hear at regular volumes.